The present invention relates to an apparatus for supplying a varnishing cylinder of a sheet varnishing machine with a varnish film and including a varnish feed roller for depositing the varnish film on the varnishing cylinder, a pressure roller cooperating with the varnish feed roller for supplying the varnish film, and a varnish basin formed between the varnish feed roller and the pressure roller, with at least one scrapper blade for scrapping varnish from the pressure roller.
Here, the term "varnishing machine" is preferably used for designating a varnishing machine for one-sided varnishing of plate-shaped metal sheets, with the sheets being displaceable between a varnishing cylinder, having an outer surface formed of rubber or another elastic material, and hard pressure cylinder, and with the varnish feed roller having an inelastic outer surface. In a corresponding printing machine or press, usually print ink is transferred from an ink feed roller to a plate cylinder. Here, a sheet varnishing machine is used, e.g., in manufacturing of drink cans, glazing caps, crown caps, where varnishing of inner and outer surfaces precedes printing, which is followed with protective varnishing. In these cases, the varnish should meet specific requirements so that the varnish, upon subsequent pressing or deep-drawing of the sheets, would not crack.
To form a stripe-shaped outer surface of a sheet for enable welding, conventionally elongate recessing doctor blades are used, from which the above-mentioned scrapper blades distinguish by their shape and function. The scrapper blades serve primarily for supplying a varnishing cylinder with a varnish film having a high uniformity, which permits to eliminate varnish splitting and phantom layering by the unused varnish field of the varnishing cylinder when a new varnish film is formed on the varnishing cylinder. Often, intermediate rollers are used which simply smudge the varnish splittings. The use of intermediate rollers increases the cost of the varnishing machines.
Austrian patent N246, 185 discloses a supplying apparatus of the above-mentioned type but relating to an inker mechanism for a printing press, in which an oil ink is used and in which the application roller, which is made of an elastic material, transfers ink onto an engraving roller. There is provided an ink scrapper for forming a dammed area for the ink substance in the vicinity of the contact line of the ink roller and the transfer roller. The scrapper is provided on the ink roller. The ink and the transfer roller are rotatable in the same direction. At that, changing of the circumferential or angular speed of the ink roller relative to the transfer roller is possible. The object of patent No. 246,185 is to provide simple means for operational control of the ink film thickness. The ink, which remains on the transfer roller, after the ink transfer to the engraving plates of the plate cylinder, is transferred back to the dammed area by the transfer roller. There is provided a second ink scrapper on the other half of the ink roller to insure a complete removal of the ink film. The transfer roller, which returns the ink back to the dammed area, is not equipped with any ink scrapper and, therefore, the unused amount of ink does not affect the formation of the new film on the plate cylinder.
The object of the present invention is an apparatus for supplying a varnishing cylinder of a varnishing machine, which would have a simple structure and would take up little space. Another object of the invention is a supplying apparatus of the above-described type in which the unused varnish field on the varnishing cylinder does not affect formation of a new film on the varnishing cylinder.
A further object of the invention is a supplying apparatus of the above-mentioned type which would insure convenient cleaning and would provide for a more rapid change of the varnish when necessary.